1. Field of the Invention
The present invention relates to weighing devices. Specifically, the invention is an apparatus for quickly and accurately weighing gunpowder. The apparatus volumetrically measures an initial powder charge close to but below the desired charge, and deposits the charge on a scale, where a dribbler slowly adds powder until the desired weight is reached.
2. Description of the Related Art
Methods of measuring or weighing granular material for accurate, consistent, and rapid dispensing have been proposed by numerous other inventors. However, none of the prior inventors within the knowledge of the present inventor has described a system wherein the granular material is first measured volumetrically in order to quickly dispense an amount close to but below the desired amount, then material is added until the exact weight is reached, whereupon the weight of the material is confirmed before dispensing it into its final container, and finally the material is dispensed into its final container while simultaneously dispensing a next volumetric measure of material onto the scale.
Like the present invention, several other proposals relate to the weighing, measuring, or dispensing of gunpowder. Shooting competitors will frequently hand-load their own ammunition in an attempt to optimize it for their particular gun and purpose. For example, high power rifle competitors, who typically engage targets as far away as 600 yards, need to have very consistent ammunition. When a gun is fired, its barrel vibrates in a sinusoidal manner. At the top or the bottom of the vibration, the barrel is relatively stable, whereas in the middle of the vibration, the barrel is rapidly moving in one direction or another. This barrel movement will result in vertical stringing of bullets on the target. Shooters will therefore attempt to find the exact type and amount of powder and correct bullet seating depth to produce exactly the right velocity so that the bullet exits the barrel at either the top or the bottom of the vibration, as determined by minimizing the vertical stringing of bullets on the target. Once the right combination is found through trial and error experimentation, the shooter will attempt to reproduce the exact combination which produced the best results. Shooters will typically weigh their powder charges to 1/10 of a grain accuracy (with 1 grain equal to 1/7,000 of a pound), corresponding to 5-6 granules of typical rifle powder. This accuracy is contrasted with typical factory loaded ammunition, which may have powder charges deviating from each other within a range of 0.5 grains. Simply using a volumetric powder measure, without weighing the powder charge, will result in powder charges deviating from each other within a range of 0.4 grains.
Producing cartridges loaded to this degree of accuracy increases the time spent hand-loading each individual cartridge, which is a very tedious process even without this added difficulty. Therefore, the speed with which the desired weight can be produced is critical, and second in importance only to the accuracy of the weighing. Accurate weighing is not only critical for accurate shooting, but also for safety. A cartridge generating greater than the SAAMI specified pressure for its caliber can result in severe damage to the gun and/or injury to the shooter.
Various devices for weighing, only generally similar in structure and unrelated to the art of loading powder charges, are known. One of the earliest examples of a granular dispensing device is described in U.S. Pat. No. 906,214, issued to Charles C. Freeman on Dec. 8, 1908. This patent describes a machine for boxing toothpicks. The machine dispenses toothpicks into a pocket on a rotating wheel. A second knurled wheel rotating the same direction prevents picks from jamming between the casing and the wheel. The first wheel dumps the picks into a V-shaped pocket formed by two plates hingedly connected to the wheel's casing. The rotation of the first wheel opens the V-shaped pocket after the required number of pockets have been emptied into the V-shaped pocket, thereby filling the box.
U.S. Pat. No. 1,978,558, issued to Ernst C. Von Pritzelwitz Van Der Horst on Oct. 30, 1934, describes an automatic weighing machine for viscous liquids. The machine dispenses liquid into a weighing vessel on one end of a beam balance; When the weight of the liquid pulls the beam balance horizontal, the inlet valve is pulled shut, and the outlet valve is opened. Various damping devices cause the balance to remain briefly in a horizontal position when empty, allowing the user to confirm the calibration.
Although U.S. Pat. No. 2,539,030, issued to Randal C. Parker on Jan. 23, 1951, describes a gunpowder weighing device, it is not similar to the present invention. The powder is fed from a hopper, through a horizontal feed screw, into the pan of a beam balance until the desired weight is reached. The powder is then dumped through a funnel leading to the cartridge casing.
Other inventions consider processes which dribble or deliver granular material more precisely. U.S. Pat. No. 2,661,876, issued to Harold V. Kindseth on Dec. 8, 1953, describes a device for automatically opening and closing the valve-acting gates of feeding hoppers for packaging machinery. The device is actuated by the weight of the material to be packaged. Material is first fed into the balance receptacle by a bulk feeding system having a feed screw at the bottom of a hopper, and then topped off by a dribble feed system. When the motor is activated, the hopper gates are opened. Once the beam balance comes close to indicating the desired weight, the bulk feeder is closed, and the dribble feeder is used to add the remaining material.
U.S. Pat. No. 2,833,506, issued to Norman R. Gunderson on May 6, 1958, describes a scale for weighing granular material. The granular material is fed from a hopper into the pan of a beam balance. A sliding weight at the other end of the beam balance is set to the desired weight. A pair of electrical contacts are located at the end of the beam having the sliding weight. The contacts act as switches for an electric vibrating mechanism comprising a speaker and a voice coil connected to the hopper. With both contacts closed, the hopper vibrates at maximum speed, filling the pan quickly. As the beam balance begins to tilt towards its balanced position, one of the two contacts moves from its closed to its open position, reducing the power available and therefore slowing the hopper's vibration. As the beam balance reaches horizontal, the second contact moves to the open position, stopping the hopper's vibration. Unlike the present invention, this invention relies on the slower process of using a rapid feed to begin dispensing material, followed by a slower speed as the correct weight is reached.
U.S. Pat. No. 3,109,561, issued to Paul Lohse and Adolf Stambera on Nov. 5, 1963, describes a weighing and dispensing device having four dispensing containers mounted on a horizontal wheel. The containers rotate between four positions. At the first position, slightly less than the target weight of pourable material is dispensed into the container. At the second station, the container is weighed. At the third station, a dispenser controlled by the scale at the second station dispenses exactly the amount of additional material needed to achieve the desired weight. At the final station, the material is dispensed into a package which is being moved along a conveyor belt below the final station. This invention does not allow any confirmation of the final weight before dispensing the material into its final package.
U.S. Pat. No. 3,134,450, issued to Roy R. Hanson on May 26, 1964, describes a weighing device for gunpowder having a beam balance with a hopper above the weighing pan. When the beam raises the pan into an upper position, a funnel is moved into position under the hopper to discharge powder into the pan. As the beam moves to the horizontal position, the funnel is moved away from the hopper, preventing further powder from reaching the pan.
U.S. Pat. No. 3,774,818, issued to Adolf Moritsovich Alexandrov, et al. on Nov. 27, 1973, describes a proportioning and charging apparatus having a batcher in the form of an eccentric rotating cylinder, and a hopper above the batcher. The batcher has a slot which is aligned with the hopper during charging, and rotates away from the hopper when the batcher is full. The hopper has a resiliently mounted deflector at the bottom, pushing excess material into the batcher and preventing jamming.
U.S. Pat. No. 3,802,522, issued to Thomas L. Thompson et al. on Apr. 9, 1974, describes a batch weighing system. The material to be weighed is transferred to the scale's pan by a conventional feeder. The amount of material in the pan is weighed, and compared with the desired weight. The amount of material dispensed by the feeder for the next batch is adjusted based on the difference between the actual and desired weight of the current batch. This invention allows for corrections only with the next batch weighed, not with the current batch, and therefore accepts some degree of inaccuracy in the current batch.
U.S. Pat. No. 3,827,513, issued to Irving Epstein on Aug. 6, 1974, describes an apparatus for measuring powder. The apparatus is a balance beam, a hopper, and an electrically powered feed screw leading from the hopper. The speed of the feed screw is determined by the position of the balance beam. A portion of the beam extends between a pair of lights and a pair of light sensors. When the beam blocks the lower light sensor from sensing the lower light, the feed screw operates at full speed. When the beam blocks both lights, the feed screw operates at half speed. When the beam blocks the upper light sensor from sensing the upper light, but allows the lower sensor to sense the lower light, the feed screw stops. Unlike the present invention, this invention relies on the slower process of using a rapid feed to begin dispensing material, followed by a slower speed as the correct weight is reached.
U.S. Pat. No. 4,292,877, issued to Richard J. Lee on Oct. 6, 1981, describes an ammunition loader. The ammunition loader's charge bar may selectively allow either powder, shot, or neither to pass from a hopper, through a metering bushing, and into a shotgun shell. If an appropriate metering bushing is not in place, the charge bar will allow material to leak when the shell is charged, providing a visual indication of the bushing's absence.
U.S. Pat. No. 4,453,610, issued to Clarence E. Purdie on Jun. 12, 1984, describes a beam balance having three weight poises. The first is on the side of the beam opposite the weighing pan, movable between graduations in one weight-unit increments. The second is on the side of the beam adjacent to the weighing pan, movable between graduations in 0.1 weight-unit increments. The third is near the end of the beam adjacent to the balance indicia, and is movable between graduations of 0.01 weight-unit increments.
U.S. Pat. No. 4,696,336, issued to Dolores D. Ellion and Max. E. Ellion on Sept. 29, 1987, describes a gun powder dispensing and measuring apparatus. The device includes a beam balance, a pair of feed screws for dispensing powder into the pan, and a sensor. One of the feed screws turns quickly for dispensing powder rapidly, and the other turns more slowly for dispensing powder more slowly. The sensor comprises a pair of light sensors opposite a pair of lights. Powder is first added to the balance's weighing pan using the rapidly turning feed screw. As the balance rotates, the balance blocks the lower sensor, changing from the fast feed screw to the slow feed screw. As the balance continues to rotate, the upper sensor is blocked, shutting off both feed screws. A spring is used to overcome the beam's initial inertia when the powder is first transferred to the pan. The spring is selected so that the force goes to zero at the time when the fast feed screw stops, and the slow feed screw starts. Unlike the present invention, this invention relies on the slower process of using a rapid feed to begin dispensing material, followed by a slower speed as the correct weight is reached, and does not address material handling considerations. Minor modifications to the basic idea described above are disclosed in U.S. Pat. No. 4,953,643, issued to Dolores D. Ellion and M. Edmund Ellion on Sept. 4, 1990, and U.S. Pat. No. 5,005,657, issued to Dolores D. Ellion and M. Edmund Ellion on Apr. 9, 1991.
U.S. Pat. No. 4,823,993, issued to Wolfgang Siegel et al. on Apr. 25, 1989, describes a bucket wheel gate for dispensing granulated material. The inlet opening has an edge for removing granular material in excess of the bucket's capacity as the bucket spins away from the inlet.
U.S. Pat. No. 4,836,315, issued to Richard J. Lee on Jun. 6, 1989, describes a balance type weighing scale having a major weight unit poise slidably mounted opposite the weighing pan, and a minor weight unit poise on the same side of the beam's pivot as the weighing pan.
U.S. Pat. No. 5,332,870, issued to Ernst Strickler on Jul. 26, 1994, describes a precision balance having a perforated funnel-shaped weighing dish for weighing flat filters. The funnel shape of the dish ensures that only the edges of the filter come in contact with the dish, preventing the deposit of residues on the weighing dish.
U.K. Pat. No. 293,636, published on Jul. 12, 1928, describes a machine for weighing and filling powdered material into bags. The material is dispensed onto a weighing container from a hopper. The downward movement of the weighing container cuts off the flow of powder and dispenses the powder into the bag as the proper weight is reached.
U.K. Pat. No. 463,064, published on Mar. 22, 1937, describes a weighing pan with an opening on top and a detachable outlet nozzle at one end.
U.K. Pat. No. 697,218, published on Sept. 16, 1953, describes a device for automatically removing batches of weighed material from a weighing machine. The device is a continuous conveyor belt which is in tension while moving materials to and from the weighing pan, and loosely rests on the weighing pan during weighing.
U.K. Pat. No. 749,399, published on May 23, 1956, describes an apparatus for cutting off the flow of material to a scale when the desired weight is reached. The device is a lever forming part of the weight indicating mechanism, which lifts a feed control mechanism to cut off the feed of material when the desired weight is reached.
U.K. Pat. App. No. 2,204,298, published on Nov. 9, 1988, describes a hopper which dispenses a fixed quantity of particulate material with each pull of a handle.
A catalog published by the mail order company MIDWAY pictures a standard rotary drum powder measure, a standard beam balance scale, and a standard electronic scale. Additionally, the catalog pictures a combination powder dispenser and electronic scale, wherein the powder dispenser is programmed to dispense a specific amount of powder onto the scale. The scale transmits weight information to the powder feeder through an infrared signal. The powder feeder uses the weight information and the dispenser's motor speed to determine the amount of powder being dispensed. The motor initially proceeds at a high rate of speed, slowing as the target weight is approached. Further details about this apparatus are found in the instruction manual for the POWDERMASTER electronic powder dispenser, and the POWDER PRO digital scale, both marketed by RCBS Operations.
None of the above publications describes a system allowing the combination of advantages of the present invention. Specifically, they do not provide the combined advantages of dispensing the previously weighed powder into its final container while simultaneously dumping a measured volume close to but below the desired weight onto the scale, adding additional powder until the desired weight is reached, automatically cutting off the flow of powder when the desired weight is reached, and allowing the user to confirm the correct weight before deciding to dump the weighed powder into the cartridge casing. None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed. Thus a granular material weighing system solving the aforementioned problems is desired.